Sprayable filler composition

ABSTRACT

A sprayable, high solids, low-volatiles filler composition is provided which may be used as a coating on a variety of substrates. The sprayable filler composition comprises a first filler/glazing component formed from a mixture of a resin, a filler, a mixture of thixotropic clays, activated fumed silica, hollow glass microspheres, and a ketone solvent. The sprayable filler composition has a second catalyst component. The glazing/filler component is blended with the catalyst component, preferably either internally or externally of the spray nozzle, and the resultant sprayable filler composition is sprayed onto a substrate. The resulting cured coating provides a sandable surface which is corrosion resistant.

This is a divisional application of U.S. patent application Ser. No.08/067,707 filed May 26, 1993 pending.

BACKGROUND OF THE INVENTION

The present invention relates to a sprayable filler composition, andmore particularly, to a high solids, low-volatiles sprayable fillercomposition which may be used as a coating on a variety of substrates,and which provides a corrosion resistant, sandable surface.

Multi-component spraying systems are widely used in the plastics andmarine industries. In such systems, a liquid resin and a catalyst forthe resin are mixed together and sprayed onto a substrate such that thecatalyst and resin react and harden on the substrate. The mixing may bedone immediately before spraying (referred to as an internal mix system)or immediately after spraying (referred to as an external mix system).In either event, such coatings are referred to as a "gel coat". Forexample, U.S. Pat. No. 4,967,956 to Mansfield discloses a "gel coat"spraying system which uses a resin such as an epoxy resin or a polyesterresin, a catalyst for the resin, and spraying means which includes anairless liquid nozzle. Such gel coats utilize a slow curing process, andthe coatings do not provide a sandable surface.

Another disadvantage of such gel coatings is that application of thecoatings is effected through the use of organic solvents to reduceviscosity. Because of increased environmental concerns about volatileorganic components (VOC's), efforts have been made to reduce the amountof volatile materials used in such coating operations. As a result, theuse of high solids coatings has been employed to meet VOC regulations.For example, White et al, U.S. Pat. No. 5,057,555, discloses a coatingcomposition having a high solids content which is used as a finish forautomobiles and trucks comprising an acrylic polymer and a catalyst.However, the coating cures very slowly. In addition, the compositionstill includes from 20-60% of an organic solvent. Further, such highsolids coatings often run and sag when applied to vertical surfaces, andthey have poor shelf and pot life.

As an alternative to using organic solvents, Bok et al, U.S. Pat. No.5,171,613, teaches using a supercritical fluid as a non-pollutingdiluent in combination with a coating mixture. However, the method ofspraying the coating requires the use of a heated spray gun to maintainthe temperature of the coating mixture.

Accordingly, there is still a need in the art for a sprayable coatingcomposition which may be easily applied to a variety of substrates,cures quickly, provides a sandable surface, and contains low volatiles.

SUMMARY OF THE INVENTION

The present invention meets that need by providing a sprayable, highsolids, filler composition containing low volatiles. The composition hasa VOC content of 74.5 g./l., which meets all current regulations. Thehigh solids content of the composition retains other desirable qualitiessuch as unlimited pot life. The sprayable filler composition of thepresent invention is a two-part one having a first filler/glazingcomponent and a second catalyst component. When the two components aremixed and sprayed (or sprayed and mixed) the resultant coating curesquickly and provides a corrosion resistant, sandable surface.Accordingly, it may be used on a variety of substrates such as on metalheavy duty vehicle bodies, on concrete as a facing, and on metal-basedbathroom fixtures such as sinks and comodes. Generally, it may be coatedon iron, aluminum, wood, fiberglass, concrete and other materials.

According to one aspect of the present invention, a sprayable, highsolids, low-volatiles filler composition for use as a coating onsubstrates is provided having a first filler/glazing componentcomprising a resin, a filler, a mixture of thixotropic clays, activatedfumed silica, hollow glass microspheres, and a small amount of ketonesolvent.

Preferably, the resin is selected from the group consisting ofunsaturated polyesters (i.e. linear polyester resins based on dibasicacids and dihydric alcohols capable of cross-linking with vinyl monomersto form thermoset copolymers), vinyl esters, epoxy resins, acrylic andpolyester polyols, and mixtures thereof. In one embodiment of theinvention, the resin is selected from the group consisting ofunsaturated polyesters, vinyl esters, and mixtures thereof, and thecatalyst component is selected from the group consisting of methyl ethylketone peroxide and benzoyl peroxide.

In an alternative embodiment of the invention, the resin comprises anepoxy resin or mixtures of epoxy resins and the catalyst component isselected from the group consisting of polyamine, mercaptan, and borontrifluoride. In yet another embodiment of the invention, the resincomprises acrylic or polyester polyols and the catalyst component isselected from the group consisting of isobiurate and isocyanurate.

Preferably, the filler is selected from the group consisting of calciumcarbonate, talc, and combinations thereof. The preferred ketone solventis acetone.

The sprayable filler composition also preferably includes a styrenemonomer to aid in curing, as well as an accelerator selected from thegroup consisting of dimethyl aniline, cobalt naphthenate, cobaltneodecanate, or mixtures thereof. The sprayable filler composition alsopreferably includes a coloring agent selected from the group of titaniumdioxide, black oxide, or mixtures thereof.

The catalyst component may be blended with the filler/glazing componentto form the sprayable filler composition which may then be sprayed onthe substrate. In an alternative embodiment, the catalyst component ismaintained as a separate component which is mixed with thefiller/glazing component during the spraying process, either internallyor externally of the spray nozzle. Preferred is an external mixdual-component spray system for mixing since it eliminates pot lifelimits.

In a preferred form, the filler/glazing component of the sprayablefiller composition of the present invention comprises: from about 20% toabout 50% by weight of a resin selected from the group consisting ofunsaturated polyesters, vinyl esters, a mixture of epoxy resins, acrylicand polyester polyols, or mixtures thereof; from about 5% to about 25%by weight of a filler; from about 1% to about 15% by weight of a mixtureof thixotropic clays; from about 0.2% to about 2% by weight activatedfumed silica; from about 1% to 15% by weight hollow glass microspheres;and from about 0% to 20% by weight of a ketone solvent.

The sprayable filler composition also preferably includes 0 to 12% of astyrene monomer, 0.2 to 2.0% of an accelerator selected from the groupconsisting of dimethyl aniline, cobalt naphthenate, cobalt neodecanate,or mixtures thereof, and from 0.2 to 4.0% of a coloring agent selectedfrom the group consisting of titanium dioxide, black oxide, or mixturesthereof.

The second catalyst component is from about 1 to 50% of a catalystselected from the group consisting of methyl ethyl ketone peroxide,benzoyl peroxide, boron trifluoride, polyamine, mercaptan, isobiurate,and isocyanurate.

In a more preferred embodiment, the sprayable filler compositioncomprises from about 35% to about 45% by weight of a resin selected fromthe group consisting of unsaturated polyesters, and vinyl esters, ormixtures thereof, 6 to 10% of a styrene monomer, 2 to 4% of a coloringagent selected from titanium dioxide, black oxide, or mixtures thereof,0.8 to 2% of an accelerator selected from the group consisting ofdimethyl aniline, cobalt naphthenate, cobalt neodecanate, or mixturesthereof; from about 10% to about 20% by weight of a filler; from about1% to about 10% by weight of a mixture of thixotropic clays; from about0.5% to about 1% by weight fumed silica; from about 2% to 10% by weighthollow glass microspheres; and from about 0% to 10% by weight of aketone solvent.

The second catalyst component of the sprayable filler compositionfurther includes 2 to 4% of a catalyst component and preferably about 3%by weight of the filler/glazing component of a methyl ethyl ketoneperoxide catalyst.

The present invention also provides a method of using the sprayablefiller composition which includes the steps of: a) forming a firstfiller/glazing component in the form of a mixture of a resin selectedfrom the group consisting of unsaturated polyesters, vinyl esters, epoxyresins, acrylic and polyester polyols, and mixtures thereof; a filler, amixture of thixotropic clays; activated fumed silica; hollow glassmicrospheres, and a ketone solvent; b) adding a second catalystcomponent to the mixture to initiate the cure of the sprayable fillercomposition; and c) spraying the sprayable filler composition through aspray nozzle onto a substrate. As mentioned, the catalyst is preferablyadded to the filler/glazing component during the spraying step.

The sprayable filler composition and method of the present inventionprovides high deposition of the coating on a substrate (either primed orunprimed) and results in a surface which is sandable, corrosionresistant, primable and paintable. In addition, because the compositioncures quickly, the overall finishing costs are reduced. Other advantagesof the sprayable filler composition of the present invention are its lowvolatiles content, and other environmentally sound features (i.e., noout gassing, no recognized carcinogenic components, no ozone depletingsubstances), its extended pot life due to its dual component nature, theability to form relatively thick (15-25 mils) single layer wet coats,and the ability to form even thicker overall coatings by applyingmultiple layers, its ability to fill major pits, grind marks, castingflaws and even large surface imperfections permitting use onrough-finish, less costly substrates, and its self-leveling ability.

Accordingly, it is an object of the present invention to provide asprayable, high solids, low-volatiles filler composition for use as acoating on substrates, which cures quickly, and provides a sandablesurface which is corrosion resistant. These and other objects andadvantages of the invention will become apparent from the followingdetailed description and the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The sprayable filler composition of the present invention provides manyadvantages over previous coatings in that it cures quickly, provides asandable surface, contains low volatiles, and is less expensive toproduce. The composition may be applied to a variety of substratesincluding metals such as iron, aluminum, concrete, wood, fiberglass andpolyester fillers, etc.

The present sprayable filler composition preferably comprises a firstfiller/glazing component including a resin selected from the groupconsisting of unsaturated polyesters and vinyl esters. Such resinsprovide fast curing and good adhesion. Suitable unsaturated polyestersare available from Reichhold Chemicals, Inc. of Research Triangle Park,Durham, N.C. under the Polylite trademark and the designation 32-374,which is a mixture of a maximum of 67% of a proprietary polyester resinand 38% of a styrene monomer (CAS #100-42-5), and which has a boilingpoint of 295° F., a volatile percentage of 33-38%, a vapor densityheavier than air, and a specific gravity of 1.10. Suitable vinyl estersinclude 8084 vinyl ester, which is a mixture of 40-50% of a styrenemonomer (CAS #000100-42-5) and the balance vinyl ester resin (CAS#068492-68-2), and which has a boiling point of 294° F., a vaporpressure of 7 mmHg at 20° C., a vapor density of 3.6 based on styrene,and a specific gravity of 1.010-1,035, and 411-35 vinyl ester, which isa mixture of 35-50% of a styrene monomer (CAS #000100-42-5) and thebalance vinyl ester resin (CAS #036425-16-8), and which has a boilingpoint of 294° F., a vapor pressure of 7mmHg at 20° C., a vapor densityof 3.6 based on styrene and a specific gravity of 1,025-1,075, bothavailable from Dow Chemical Company of Midland, Mich. under the Derakanetrademark. Other suitable resins for use in the present inventioninclude epoxy resins, specifically Bisphenol-A type resins availablefrom Reichhold Chemicals, Inc. under the Epotuf trademark and thedesignation 37-140, which is 100% of a Bisphenol-A diglycidyl ether (CAS#25085-99-88) and which is non-volatile and has a specific gravity of1.16.

A styrene monomer is preferably included in the filler/glazing componentto increase the rate of polymerization and to reduce the viscosity ofthe composition. However, it should be noted that in instances wherevinyl esters are used as resins, an encapsulated petroleum based waxshould be used in place of some of the styrene. Suitable waxes includeBYK S-740 available from Byk Chemie.

The thixotropic clays suitable for use in the filler/glazing componentof the present invention include prewet and dry organo clays. A suitableprewet clay is available from Rheox, Inc. under the trade name MPA-60-x.A preferred dry clay is quaternary ammonium bentonite, available fromUnited Catalysts, Inc. under the trade name Advitrol 6-8. The prewetclay acts as an antisettling agent and also provides thixotropicproperties to the composition while the dry clay provides fast shearviscosity, and also provides thixotropic properties.

Fumed silica is included in the filler/glazing component to provide fastviscosity, and also acts as a thixotropic agent. The fumed silica iscommercially available from DeGussa Company under the trade name Aerosil200. The fumed silica is preferably activated by the addition ofethylene glycol.

The preferred fillers for the filler/glazing component of the presentinvention include talc and calcium carbonate. These fillers providethixotropic properties to the composition and also aid in providingsanding properties to the coated substrate. A preferred talc is MP25-38available from Pfizer. Calcium carbonate is commercially available fromGenstar under the trade name Camel Wite.

Preferably, the filler/glazing component includes a coloring agent toform a colored finish. Suitable coloring agents include black ironoxide, available from Pfizer, and titanium dioxide (Rutile), availablefrom SCM Chemicals under the designation Tiona RCL-9.

The filler/glazing component also preferably includes acceleratingagents to speed up the curing time. Suitable accelerators includedimethyl aniline, available from Dupont under the designation N,N DMA,and cobalt naphthenate or cobalt neodecanate, available from MooneyChemical, Inc. under the designation TEN-CEM.

The preferred ketone solvent for the filler/glazing component isacetone, which evaporates quickly, and also reduces the viscosity of thesprayable filler composition.

The hollow glass spheres used in the filler/glazing component of thepresent invention provide an excellent sanding surface, reduce theweight and cost of the filler composition, aid in thixotropy, andprovide a tooth which assists in the application of subsequent coatings.Preferred for use are hollow glass spheres available from 3M Companyunder the trade name E-22-X Bubbles.

Based on the foregoing, the preferred filler/glazing component of thesprayable filler composition comprises: from about 20% to about 50% byweight of a resin selected from the group consisting of unsaturatedpolyesters, vinyl esters, a mixture of epoxy resins, acrylic andpolyester polyols, or mixtures thereof; from about 5% to about 25% byweight of a filler; from about 1% to about 15% by weight of a mixture ofthixotropic clays; from about 0.2% to about 2% by weight activated fumedsilica; from about 1% to 15% by weight hollow glass microspheres; andfrom about 0% to 20% by weight of a ketone solvent. The filler/glazingcomponent also includes from 0 to 12% of a styrene monomer, 0.2 to 2% ofan accelerator selected from the group consisting of dimethyl aniline,cobalt naphthenate, cobalt neodecanate, or mixtures thereof, and from0.2 to 4% of a coloring agent selected from the group consisting oftitanium dioxide, black oxide, or mixtures thereof.

The sprayable filler composition further includes as the catalystcomponent from 1 to 50% of a catalyst selected from the group consistingof methyl ethyl ketone peroxide, benzoyl peroxide, boron trifluoride,polyamine, mercaptan, isobiurane, and isocyanurate.

More preferably, the sprayable filler composition fillerglazing/component comprises: from about 35% to about 45% by weight of aresin selected from the group consisting of unsaturated polyesters andvinyl esters, or mixtures thereof, 6 10% of a styrene monomer, 2 to 4%of a coloring agent selected from titanium dioxide, black oxide, ormixtures thereof, 0.8 to 2% of an accelerator selected from the groupconsisting of dimethyl aniline, cobalt naphthenate, cobalt neodecanate,or mixtures thereof; from about 10% to about 20% by weight of a filler;from about 1% to about 10% by weight of a mixture of thixotromic clays;from about 0.5% to about 1% by weight fumed silica; from about 2% to 10%by weight hollow glass microspheres; and from about 0% to 10% by weightof a ketone solvent.

The sprayable filler composition further includes from 2 to 4% of acatalyst component.

The present invention also provides a method by which the sprayablefiller composition is used. The present method preferably comprises thesteps of: a) forming a filler/glazing component of the sprayable fillercomposition from a mixture of a resin selected from the group consistingof unsaturated polyesters, vinyl esters, epoxy resins, acrylic andpolyester polyols, and mixtures thereof; a filler, a mixture ofthixotropic clays; activated fumed silica; hollow glass microspheres,and a ketone solvent; b) adding a catalyst component to thefiller/glazing component to form the sprayable filler composition, andc) spraying the sprayable filler composition through a spray nozzle ontoa substrate. In one embodiment, the catalyst component is added to thefiller/glazing component during the spraying step. The catalystcomponent may be mixed with the filler/glazing component during thespraying process, either internally or externally of the spray nozzle.For example, the catalyst component can be sprayed with thefiller/glazing component and blended externally using a dual spray gunsuch as the PRED/FRP equipment from Binks of Franklin Park, Ill.

Once the catalyst component is mixed with the filler/glazing componentand the sprayable filler composition sprayed onto a substrate thecomposition gels in about 1.5-2.5 minutes and is tack free in 8-10minutes at 73° F. The cured composition provides a sandable surfacewhich is resistant to corrosion. In addition, the resulting finish doesnot require sanding or a sealer prior to the application of top coats.Accordingly, the filler composition may be used for a variety ofapplications including leveling uneven surfaces such as pits, grindmarks, casting flaws, and large surface imperfections.

In order that the invention may be more readily understood, reference ismade to the following example, which is intended to be illustrative ofthe invention, but is not intended to be limiting in scope.

EXAMPLE 1

The filler/glazing component of a sprayable filler composition wasprepared in accordance with the present invention. The relativeproportions of each component is shown in Table I below.

                  TABLE I                                                         ______________________________________                                        Compound Description % by weight                                              ______________________________________                                        unsaturated polyester.sup.1                                                                        38.3                                                     unsaturated polyester.sup.2                                                                        7.3                                                      styrene monomer      3.9                                                      organic thixotropic clay.sup.3                                                                     4.1                                                      black iron oxide     0.02                                                     quaternary ammonium bentonite.sup.4                                                                0.44                                                     titanium dioxide rutile.sup.5                                                                      2.45                                                     micro talc.sup.6     14.68                                                    calcium carbonate.sup.7                                                                            9.79                                                     fumed silica.sup.8   0.73                                                     12% cobalt neodecanate.sup.9                                                                       0.91                                                     dimethylaniline.sup.10                                                                             0.32                                                     Bis A-epoxy.sup.11   0.61                                                     Ethylene glycol      0.20                                                     acetone              4.78                                                     hollow glass spheres.sup.12                                                                        7.34                                                     ______________________________________                                         .sup.1 32374 from Reichold Chemicals, Inc.                                    .sup.2 92955 from Reichold Chemicals, Inc.                                    .sup.3 MPA60-x from Rheox, Inc.                                               .sup.4 Advitrol 68 from United Catalysts, Inc.                                .sup.5 Tiona RCL9 from SCM Chemicals                                          .sup.6 MP2538 from Pfizer                                                     .sup.7 Camel Wite from Genstar                                                .sup.8 Aerosil 200 from DeGussa Company                                       .sup.9 TenCem from Mooney Chemical, Inc.                                      .sup.10 N,N DMA from DuPont                                                   .sup.11 37140 from Reichold Chemicals, Inc.                                   .sup.12 E22-X Bubbles from 3M Company                                    

The filler composition was prepared by mixing all of the above-listedcomponents. The resulting filler/glazing component was a thixotropicfree flowing liquid having a viscosity approximately 1500-2500 cps (LVT#3 at 30 RPM). Its wt/gal was approximately 7.8-8.2 lbs/gallon, itsvolatile content (VOC) was 0.62/lb/gal or 74.5 g/l, and its pot lifeinfinite.

A methyl ethyl ketone peroxide catalyst component at 3% by weight of thefiller/glazing component was then added to the filler/glazing componentto form a sprayable filler composition and sprayed onto a substrateusing external mix Gelcoat spray equipment from Binks of Franklin Park,Ill. After spraying, the gel time was measured at about 1.5-2.5 minutes.The coating was tack free in 8-10 minutes at 73° F. It had an averagedry coat thickness of 15-25 mils (20 avg), a sand time of 30-45 minutesat 73° F., greater than 500 hours of 5% salt fog corrosion resistance,greater than 300 hours of 100% humidity corrosion resistance. Thecoating may be primed and/or top coated (painted).

While certain representative embodiments and details have been shown forpurposes of illustrating the invention, it will be apparent to thoseskilled in the art that various changes in the methods and apparatusdisclosed herein may be made without departing from the scope of theinvention, which is defined in the appended claims.

What is claimed is:
 1. A sprayable, high solids, low-volatiles fillercomposition for use as a coating on substrate comprising:a) afiller/glazing component comprising a mixture of from about 20% to about50% by weight of an unsaturated polyester resin, from about 5% to about25% by weight of a sprayable filler selected from the group consistingof calcium talc, and combinations thereof, from about 1% to about 15% byweight of a mixture of thixotropic clays, from about 0.2% to about 2% byweight activated fumed silica, from about 1% to about 15% by weighthollow glass microspheres, from about 0% to about 20% by weight of aketone solvent, and b) a catalyst component, whereby the sprayable, highsolids, low-volatiles filler composition is able to form relativelythick single layer wet coats of from 15-25 mils, is able to fill majorpits, grind marks, casting flaws and even larger surface imperfectionspermitting use on rough-finish, less costly substrates, and has aself-leveling ability, andwhereupon after spraying and curing said upona substrate, the composition provides corrosion resistance and asandable surface upon said substrate.
 2. The sprayable fillercomposition of claim 1 wherein said catalyst component is selected fromthe group consisting of methyl ethyl ketone peroxide and benzoylperoxide.
 3. The sprayable filler composition of claim 1 wherein saidcatalyst component is a separate component which may be blended withsaid filler/glazing component during spraying either internally orexternally of the spray nozzle.
 4. The sprayable filler composition ofclaim 1 wherein said filler/glazing component includes a coloring agentselected from the group consisting of titanium dioxide, black ironoxide, and mixtures thereof.
 5. The sprayable filler composition ofclaim 1 wherein said filler/glazing component further includes anaccelerator selected from the group consisting of dimethyl aniline,cobalt naphthenate, cobalt neodecanate, and mixtures thereof.